This invention relates to a container for transporting temperature sensitive materials, and more specifically to a container which is adapted to maintain its interior at a desired temperature irrespective of ambient conditions outside the container, whether such conditions be of significantly higher or lower temperature than the desired temperature.
Although the following description relates mainly to the provision of a container for transporting temperature sensitive materials at a temperature which is below that of the normal ambient conditions to which the container may be subjected, it is to be mentioned that the container hereafter described may equally be used to transport materials at a substantially constant temperature which is generally above that of the normal ambient conditions, and the invention should not be considered as limited to either circumstance. Typical examples would include the transportation of temperature sensitive materials, e.g. blood or other biological matter or injectable fluids or solid matter, in typically cold or hot climates, for example in extreme northern or southern countries where temperatures regularly fall below 0xc2x0 C., or equatorial or tropical countries where the temperatures regularly rise above 25xc2x0 C. or more.
U.S. Pat. No. 5,435,142 to Silber describes apparatus for packaging temperature sensitive materials for transportation. The apparatus described includes an insulating container which are assembled from a corrugated fibre board carton inside which slab-like foam or polystyrene insulating blocks are disposed to define an inner chamber which completely surrounded by the insulating material. The insulated chamber is capable of holding two frozen bottle style refrigerant packs against its inner lined side wall and two refrigerated brick style refrigerant packs against its top and bottom lined walls to create a cooling chamber within which temperature sensitive materials, also housed in a flexible foam insulation lined container are cooled by a heat transfer cooling mechanism which is capable of maintaining the temperature of the stored materials in the range 2xc2x0 C. to 10xc2x0 C. for several hours regardless of the ambient temperatures or conditions exterior to the container.
A fundamental disadvantage of the abovementioned container is that it can operate only in a xe2x80x9cpassivexe2x80x9d manner. Hence, although the container is designed to insulate the interior chamber from the external atmosphere for a predetermined period of time and to maintain the temperature of that interior at a predetermined level for a certain period of time, it is generally impossible to set the desired temperature of the interior at a predetermined level prior to depositing the material into the chamber.
Additionally, although the specification does imply that the temperature of the material stored in the container may be maintained at a level in the range mentioned above for a certain time period, it is not possible to prevent the temperature within the chamber from dropping beneath the lower limit in circumstances where the container is exposed to very low ambient temperatures for significant periods of time. This is often the case in harsh climates where containers of this type are delivered to premises without being received, and the container is merely left outside for later collection. Alternatively, there are instances where containers of this type are transported in vehicles having dedicated refrigeration or freezing compartments for transporting chilled or frozen produce. The difficulty with the transportation of goods in such vehicles is that the temperature of the compartment in which the goods are being transported is usually uniform for all goods contained therein, and therefore unsuitable where the particular material to be transported is particularly sensitive to temperature, for example where deviations from the required transportation temperature of the material can cause significant or immediate degradation of the material.
It is also worth noting that containers which are transported in the cargo holds of aircraft are typically exposed to much lower temperatures, and the container described may be of particular use in these circumstances.
It is therefore an object of the present invention to mitigate against such disadvantages by providing a container within which is defined an insulated inner chamber whose temperature can be accurately set and controlled, and which furthermore is capable of being maintained for long periods of time, particularly where the container is to be used in climates where ambient temperatures are typically very low.
According to the invention there is provided a container consisting of at least a body and a lid, said body having one or more side walls and a base which together define a chamber internally of said body and an opening at one end of said body over which said lid can be disposed to close the chamber, said chamber having therein a pre-frozen or refrigerated cooling pack, characterized in that a laminar panel is affixed to at least a portion of the inner surface of one of the side walls and/or to base, said laminar panel comprising an electrically resistive component and electrical connections through which power can be delivered to said laminar panel to heat same, and further characterized in that battery powered control circuitry is also provided, said control circuitry communicating with temperature measuring means disposed within the chamber that may include user adjustable means for setting the desired temperature within the chamber, said control means acting to deliver electrical power to the laminar panel to heat same and thus increase the temperature inside the chamber when the temperature measuring means indicates that the temperature is below the desired temperature.
In an alternative aspect of the invention, the control circuitry need not be provided with user adjustable means, but instead may be provided with hardwired components which automatically set the desired temperature exactly without the facility for adjustment thereof. Of course in this instance, the container can only be used to store temperature sensitive materials whose condition is maintained substantially unimpaired at the particular temperature dictated by the control circuitry.
Preferably, the container is quadrangular having four sides and a base, and is most preferably square or rectangular.
Ideally, the laminar panel covers at least the whole of one inner surface of one side wall of the chamber, and most preferably a pair of laminar panels having electrically resistive components therein are provided over the inner surfaces of one or two of the side walls of the container.
Preferably the laminar panel comprises an electro-conductive textile layer which ensures that the panel can remain thin and does not significantly reduce the volume of the chamber.
Most preferably the control circuitry is disposed within the chamber and proximate the laminar panel, and yet further preferably the electrical connection between the control circuitry and the batteries which power said control circuit and said laminar panel are in the form of wires which pass through one of the walls or the base of the container. Most preferably, the one or more batteries are disposed in a recess formed in the outer surface of one of the walls, base or lid of the container.
It is still further preferable that the container is self contained in that it does not require any external electrical connection for effective operation but is capable of being so connected if so desired.
Most preferably the container, is disposed within a carton board or corrugated cardboard liner.